Process of making pressure sensitive record material



Patented Apr. 25, 1950 UNITED STATES PATENT OFFICE.

PROCESS OF MAKING PRESSURE SENSITIVE RECORD. MATERIAL Barrett 'K-. Green, Dayton, Ohio, assignor to The National CashRegister Company, Dayton, Ohio, a corporation ofMar-yland I No Drawingx Original application November 8; .1947, Seria1;N0..784,939. Divided and'this'ap plication December 2, 1948, Serial No. 63,216

This invention relates to improvements in process of making a pressure-sensitive record material. This application is adivision of the pending application of Barrett K. Green, Serial No. 784,939, filed November 8, 1947, for Process of making pressure-sensitive'record material.

The principal object of this invention is to provide a process of making a pressure-sensitive record material, on which a mark of distinctive color may be :produced by the mere application 1y reactive to produce a distinctive color in the record material at the points of application of localized pressure thereto, such pressure rupturing the insulatin medium to permit chemical reaction between :the two liquid reagents. The two reagents disclosed in-this tpatent are gallic acid and ferric ammonium sulphate, each dissolved in glycerine. These reagents are ionized bythe glycer-ine, which constitutes an ionizing medium, and the 'chemical reaction proceeds by'interchange of ions when the two solutions-are allowed tomixfupon the rupture of the insulating medium, The reaction disclosed-in thatpatent de pends upon the presence of the-reagents in an ionizing medium. However,anys available ionizing-medium is hydroscopic, with-the result that Another object of the presentinven'tion 'is to provide -a process of making afrecord material up'onwhich-a mark of distinctivecolor may be produced, at the points of application of localized pressure thereto, "by 'suchmere application of localized pressure, and which will not become discolored or stained due to the 'efiect of light, atmospheric conditions, or aging.

Inshort, it is the object of this inventionto rovide a processof making apressure sensitive record material in which the mark of distinctive color willbe produced-only at the points of application of localized pressure, and. at no other points, and under no other conditions.

Another object of this invention'is to provide, a process of making apressure-sensitive record.

material in which the mark of distinctive coloris produced by the chemical reaction of color-forming reactants, in the absence of any liquid ionizing medium therefor.

A further object of this invention is toprovide a process of making a pressure-sensitive record material in which a mark of distinctive color is produced by a reaction between solid particles of color-forming reactants.

Further objects, and objects relating to details and economies of operation, will definitely appear from the detailed description tofollow. The objects of this invention have been attained by the several embodiments thereof described in detail in-the following specification. This invention is clearly .definedand pointed outin the appended claims. I

In general, the present invention contemplates a process of making a pressure-sensitive record material including-the forming on a supporting member a film-like deposit of solid particles of a plurality of adsorption color-forming reactants disposed in contiguity with each other, such reactants being so selected that they react, in the absence of a liquid ionizing medium for the reactants, to form a distinctive color when brought into contact with each other, and a solid insulatin medium insulating said reactants from colorforming reaction contact with each other. Upon application of localized pressure to the record material, as by drawing a stylus across'it, the insulating medium is ruptured at the points of application of said localized pressure, and such ruptur'e permits color-forming reaction contact f The color reaction employed is of the, so-called; adsorption type wherein an inorganic'compound causes a color change in an organic compound coming into contact therewith.

Of the reactant materials employed the organic' material is "an electron donor aromatic compound According to one embodiment of the invention, solid particles of one of the color-forming re-,

actants are carried by and dispersed in a solid insulating medium, to which a coating of solid particles of another color-forming reactant is applied. In this case, the application of localized pressure ruptures the solid insulating medium, 5

at the points of application of such pressure, and brings about color-forming reaction contact between the solid particles of color-forming reactants at such points, thus producing the mark of distinctive color. Preferably, this pressuresensitive record material includes a base web, such'as a fibrous web of paper or the like, to which the coating of solid insulating medium an the color-forming reactants is applied.

The insulating medium is a pressure-rupturable filmderived from an organic film-forming hydrophilic colloid substance.

Since it is diilicult to show precisely the spatial relationship between the solid particles of colorforming reactants, the solid insulating medium,

and the base web, it is preferred not to attempt to illustrate any embodiment of this invention by drawings. 1

In the following examples, there will be described embodiments of this invention, by means of which the objects of the invention have been successfully attained.

A preferred embodiment of this invention produces a pressure-sensitive record material comprising a web of paper having applied thereto a'coating including casein as the solid insulating medium and solid particles of two color-' forming reactants; namely, kaolin and the compound 3,3 bis(p-methylaminophenyl) phthalide, having the structural formula,

' CHaHN- NHCHa This record material is normally white, but the application of localized pressure thereto ruptures the insulating medium, casein, at the points of application of such pressure, permitting colorforming reaction contact between the solid particles of kaolin and the solid particles of the compound 3,3 bis(p-methylaminophenyl) phthalide, resulting in the production of a bright blue mark. i 7

The record'material just described has been successfully made, in accordance with this embodiment of the invention, by coating a web of paper with a casein solution having solid particles of kaolin dispersed therein, the ratio of kaolin to casein being about ten to one. The paper so coated was dried and the coated side of the paper treated with a 3% solution in toluene of the compound 3,3 bis(p-methylaminophenyl) phthalide. The excess of solution was removed, and the treated paper was dried to evaporate the solvent.

The compound 3,3 bis(p-methylaminophenyl) phthalide, above referred to, is described and claimed in the pending application of Clyde S. Adams, Serial No. 588,077, filed April 12, 1945, now Patent No. 2,474,084 for Secondary amines of 3,3 bis(p-aminophenyl) phthalide.

Another embodiment of this invention produces a pressure-sensitive record material consisting of aw'eb of paper having applied thereto a coating consisting of casein as the solid insulating medium and solid particles of two color-forming reactants; namely, kaolin and the compound 3,3 bis(p-ethylaminophenyl) phthalide, having the structural formula 2H5) N- NH 21-15) This record material is normally white, but the application of localized pressure thereto ruptures the solid insulating medium at the points of application of such pressure, thus permitting color-forming reaction contact between the solid particles of kaolin and 3,3 bis(p-ethylaminophenyl) phthalide, resulting in a bright blue mark.

The record material above described was successfully made, in accordance with this embodiment of the invention, by coating a web of paper with a casein solution having solid particles of kaolin interspersed therein, the ratio of kaolin to casein being about ten to one. The coating so applied having been dried, the coated side of the paper was treated with a 3% by weight solution in toluene of the compound 3,3 bis(p-ethylaminophenyl) phthalide. The excess of this solution was removed and the treated paper dried to evaporate the solvent. 1 The compound 3,3 bis(p ethylaminophenyl) phthalide, above'referred to, is described and claimed in the pending application of Clyde S. Adams, Serial No. 588,077, filed April 12, 1945, now Patent No. 2,474,084 for Secondary amines of 3,3 bis(p-aminophenyl) phthalide.

When the ingredients of either embodiment are applied to the paper as a coating thereon, such coating should weigh about .0023 pound per square footof surface and should have a thickness of the order of from .0005 to .001 inch. The thickness of the coating varies, of course, with the treatment to which the record material is subjected in finishing. The solid particles of kaolin in this record material may be of about the order of ten microns in diameter, although considerable variation in particle size is possible without any ill effects. Particle size of the phthalide material is largely determined by the method. of. application of that ingredient; The particles of these reactants may be as large as ten microns in diameter and frequently are much smaller.

Other organic film-forming hydrophilic materials such as gelatin, methyl cellulose, starch, polyvinyl alcohol, and animal glue are representative materials that may be substituted for casein as the solid insulating medium. Any of the following inorganic materials may be substituted for kaolin as one of the color-forming re actants: attapulgite (Attapulgus clay), pyrophyl lite, talc, bentonite, halloysitc, calcium sulphate, calcium citrate, magnesium trisilicate, zinc supphide, zirconium dioxide, calcium phosphate, barium sulphate, and calcium fluoride. When any of these materials are substituted for the kaolin in this combination, the resulting record material will be white or bluish white in color, and a bright blue mark will appear thereon as the result of the application of localized pressure.

A method that has been used successfully to make the pressure-sensitive record material described above is as follows: A slurry of kaolin and water was prepared including fifty parts by weight of kaolin to fifty parts by weight of water, a

and a small amount of a suitable dispersing agent, such as sodium metaphosphate, for instance, in the proportion of 0.075% by weight was added to facilitate the dispersion of the particles of kaolin throughout the slurry. this dispersing agent reduces the viscosity of the slurry considerably, thus facilitating its mixing and application, and also preventing the settling of the solid particles of kaolin. A 20% by weight solution of casein in water was formed I.

by, first, dispersing the casein in cold water by stirring for fifteen minutes at room temperature and, then, heating up to 60 degrees centigrade. Five parts by weight of a 28% ammonium hydroxide so1utionthat is, one having a specific :7

gravity of 25.9 B., at

2G T C.

were then added to the hot casein solution,

which was stirred for about fifteen minutes and casein, and, at this stage, a small percentagefor instance, about 0.95% by weight-of a solution of equal parts by weight of tributyl phosphate in alcohol, or other anti-foaming agent, was added. This mixture of the kaolin slurry and the casein solution was then applied as a coating to the paper, and the coated paper was dried and calendered or treated in any desired way to give the proper surface finish. A solution in toluene of about 3% by weight of the selected phthalide material was then applied to the coated side of the paper, the excess of this solution was removed in any suitable way, as by passing under a doctor blade, and then the treated paper was dried to evaporate the toluene, and was ready for use.

The pressure-sensitive record materials disclosed herein are not claimed in this application but are disclosed and claimed in the pending application of Barrett K. Green, Serial No. 784,938,

filed November 8, 1947, for Pressure-sensitive i record material, and in a division, Serial No. 59,427, filed November 10, 1948.

It is understood that the process of making a pressure-sensitive record material described herein is susceptible of considerable variation without departing from the spirit of the invention.

What is claimed is:

1. The process of making a pressure-sensitive record material including the forming on a sup- The addition of iii porting member a film-like deposit of solid particles of a plurality of adsorption color-forming reactants disposed in contiguity with each other and. a solid insulating medium, derived from an organic film-forming hydrophilic colloid substance, insulating said reactant particles from color-forming reaction with each other, at least one of said reactants being an inorganic compound and at least another of said reactants being an organic compound adsorbable therewith, and said reactants being so selected as to react, in the absence of a liquid ionising medium for the reactants, to form a distinctive color when rought into adsorption contact with each other, one of said color-forming reactants, having the structure RHN NER- wherein R is selected from the group consisting of CH3 and CzHs and the inorganic reactant being in fine particle form providing a large adsorbent surface area and which is an acid relative to the organic reactant so as to be an electron acceptor when in adsorption contact with said organic reactant.

2. The process of making a pressure-sensitive record material including the steps of coating a supporting member with a film of solid insulating material, derived from an organic film-forming hydrcphilic colloid substance, having particles of a first color-forming solid reactant dispersed therein, and depositing on said film particles of a second color-forming solid reactant, one of said reactants being an inorganic compound and the other of said reactants being an organic compound adsorbable therewith, and said reactants being so selected as to form a distinctive color when brought into adsorption contact with each other, said solid insulating material being such as to insulate the reactants from color-forming reaction contact with each other, and said second color-forming reactant, having the structure RHN NHR REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Great Britain Jan. 4, 1943 Number 

1. THE PROCESS OF MAKING A PRESSURE-SENSITIVE RECORD MATERIAL INCLUDING THE FORMING ON A SUPPORTING MEMBER A FILM-LIKE DEPOSIT OF SOLID PARTICLES OF A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS DISPOSED IN CONTIGUITY WITH EACH OTHER AND A SOLID INSULATING MEDIUM, DERIVED FROM AN ORGANIC FILM-FORMING HYDROPHILIC ONLOAD SUBSTANCE INSULATING SAID REACTANT PARTICLES FROM COLOR-FORMING REACTION WITH EACH OTHER, AT LEAST ONE OF SAID REACTANTS BEING AN INORGANIC COMPOUND AND AT LEAST ANOTHER OF SAID RECTANTS BEING AN ORGANIC COMPOUND ADSORBABLE THEREWITH, AND SAID REACTANTS BEING SO SELECTED AS TO REACT, IN THE ABSENCE OF A LIQUID IONIZING MEDIUM FOR THE REACTANTS, TO FORM A DISTINCTIVE COLOR WHEN BROUGHT INTO A ADSORPTION CONTACT WITH EACH OTHER, ONE OF SAID COLOR-FORMING REACTANTS, HAVING THE STRUCTURE 